基于末位淘汰GSGA算法的平顶光束整形研究  

Research on Flat Top Beam Shaping Based on Lowliest Place Elimination GSGA Algorithm

作　　者：张昱冬 赵秋烨 方振 张祖兴[1] Zhang Yudong;Zhao Qiuye;Fang Zhen;Zhang Zuxing(College of Electronic and Optical Engineering&College of Flexible Electronics(Future Technology),Nanjing University of Posts and Telecommunications,Nanjing 210023,Jiangsu,China)

机构地区：[1]南京邮电大学电子与光学工程学院、柔性电子(未来技术)学院,江苏南京210023

出　　处：《中国激光》2024年第6期142-148,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金(62175116);南京邮电大学1311人才计划、大学生创新创业训练计划(202210293016Z)。

摘　　要：激光技术发展迅速,在医疗、生物、军事和材料等领域应用广泛,但激光光强的高斯型分布限制了激光的进一步应用。平顶光束整形技术应运而生并受到广泛关注。针对该问题,提出了基于末位淘汰制(LPE)、Gerchberg-Saxton(GS)算法和遗传算法(GA)的LPE-GSGA算法,优化空间光调制器的相位分布函数,将高斯光束整形为平顶光束。仿真结果表明,LPE-GSGA算法输出光束指标优于GS、广义自适应加性(GAA)、加权GS(GSW)和GSGA算法。与GS算法比较,LPE-GSGA算法的误差平方和(SSE)指标降低10.1%、拟合系数η提升0.85%,对相位初值的依赖程度约降低1个数量级,输出光束顶部光强突变点更少、旁瓣减少且幅度更低。LPE-GSGA算法减少了对初值的依赖程度,使高能量利用率、高光束顶部均匀度的平顶光束整形成为可能。Objective With the rapid development of laser technology,it has been widely applied in important fields such as medicine,biology,materials and national defense.The amplitude of a laser beam generally has a Gaussian distribution,and such an uneven energy limits its further application.Thus,beam shaping techniques have been proposed to transform Gaussian beams into flat top beams with a uniform energy distribution.Researchers have proposed various beam shaping methods,among which shaping using liquid crystal spatial light modulators has been widely investigated for its controllable transmittance function,good flexibility and realtime performance.Traditional phase distribution algorithms suffer from the problems of being easily trapped in local extrema,being sensitive to the initial value of the phase,and not being able to obtain high utilization of energy and high beam top uniformity at the same time.In this paper,the phase distribution function algorithm where beam is shaped using liquid crystal spatial light modulators is optimized by using the combination of lowliest place elimination(LPE),genetic algorithm(GA)and Gerchberg-Saxton(GS)algorithm.The hybrid method is called LPE-GSGA algorithm,which further improves the output beam top uniformity without sacrificing the utilization of energy,or even improving it.Meanwhile,it reduces the dependence of conventional algorithms on initial values to a certain extent and has important applications in flat top beam shaping with high utilization of energy and high beam top uniformity.Methods The LPE-GSGA algorithm designed in this paper uses the strong global search capability of the GA algorithm to help the GS algorithm to jump out of local extrema.Also,LPE is introduced to retain individuals with good phase points and accelerate convergence.Sum of squares for error ess and fitting coefficientηare used as evaluating indicators to describe the quality of output beams.The algorithm can be divided into two processes:the first is the iterations of all initial phase groups usi

关 键 词：激光光学 光束整形 平顶光束 LPE-GSGA算法 

分 类 号：O436.1[机械工程—光学工程]